Transcript
• GSM ArchitectureGSM Fundamentals
•At the end of this learning element, the student should be able to:
– Name the three subsystems of GSM.– List eight different network elements (generic architecture) and
name at least one task per element.– Describe the benefits of a Release 4 core network.
Objectives
•Where is the subscriber
•Who is the subscriber
•What does the subscriber want
•Information about the subscriber
Mobile Subscriber
The Mobile Station MS
GSM Mobile Station
A
NMSNMS
NSSNSSBSSBSSO&M
Air
MS
Network Switching Subsystem
• Switching• Mobility Management• Connection Management• Charging
Base Station Subsystem• Radio Resource Management• Radio Link Management
Network Management System
• Fault Management• Configuration Management• Performance Management
GSM PLMN Organization
GMSC
VLR
MSC
HLR
HLR
AC
EIR
MSC Mobile services Switching CentreGMSC Gateway MSCVLR Visitor Location RegisterHLR Home Location RegisterEIR Equipment Identity RegisterAC Authentication Centre
Network Switching Subsystem
MSC GMSC• Call control• Mobility management• Initiation of paging• Collection of changing information• Often associated with VLR
• Call control• Interrogation of HLR• Collection of changing information• Often used for interworking with external networks
Mobile services Switching Centre (MSC)
VLR• Identification numbers of subscribers• Security information• Services that the subscriber can use
HLR• Subscriber Profile• Routing Information
AC• Data for authentication (SIM)
and ciphering
EIR• Lists for Mobile Equipment (ME) checks
Registers in the NSS
SRRiDatabase
HLR HLR
MSCSGSN
MSISDN1 - rerouting info
MSISDN2 - rerouting info
.
.
1
………
Othernetworks
Mobile Number Portability Solution - SRR
PSTN
MSC Server
Site 1R
NC
2
RN
C2
MG
W
Site 2R
NC
3
RN
C3
MG
W
Site 3
RN
C4
RN
C4
MG
W
Site 4
Inter-Site
Transport
Network
Only control plane is routed to the core network site
User plane is optimized between access network sites
User plane is optimized within the same access network site
POI
User plane is optimized for PSTN
calls
MSC Server + MGW Concept (Separation of control and user plane traffic)
HLR
MSC-Server
GMSC-Server
CS-MGW
CS-MGW
UTRAN
GERAN
PSTN, ISDN,PLMN, etc.
CSE
CAP CAP
Iu
IuA
A
D C
Nc
Nb
Mc(H.248)
Mc(H.248)
Rel-04 Architecture
Base Station Subsystem
• Elements: – Base Station Controller (BSC), Base Transceiver Station (BTS), and
Transcoder and Rate Adaptation Unit (TRAU, TC)• Functions:
– Radio path control, BTS and TC control, synchronisation with MSC– Air and A interface signaling, connection establishment MS-NSS– Mobility management, speech transcoding– Collection of statistical data
BTS
TCBSC
BSC
TCBTS
BTS
Base Station Controller (BSC)
– Connection establishment between MS and NSS– Mobility management– Statistical raw data collection– Air- and A-interface signaling support – BTS and TRAU Control
BSC
Base Transceiver Station (BTS)
– Air interface signaling – Ciphering– Speech processing (channel coding, interleaving, and burst formatting)– Generation of alarms and statistics– Baseband/Radio frequency transformation
Omnidirectional BTS
f1,f2, f3
3 sectorized BTS
2 sectorized BTS
f2
f1, f2
f5, f6
f1
f3, f4
BTSBTS
BTS
BTS
BTS BTS
f = carrier frequency band
Omnidirectional and Sectorized Cells
A InterfaceA ter’ Interface
A ter Interface
MSC
SM2M
TC
TC
TC
TC
Transcoder andSubmultiplexer (TCSM)BSC
Position of the Transcoder
Data CommunicationsNetwork
BTS
BTS
BTS
BTS
DN2
BSC
MSCVLR
HLRACEIR
SMSC
NMS/2000
Network Management Subsystem
Functions of NMS (1)
•Fault management– Collection of alarm reports from network elements.– One point for managing all fault situations.
Functions of NMS (2)
•Configuration management– Management of radio network configuration.– Maintain up to date information on the network element
status.
Functions of NMS (3)
•Performance management– Collection of measurement data from network elements.– Produce performance result from raw data.
BSC
TCBTS
BTS
VLR
(G)MSC
EIRHLR AC
Um
AAterAbis
B C
D
VLRG
F
(G)MSC
E
BSS NSS
BSC
TCBTS
BTS (G)MSC
Um
AAterAbis
B C
DVLR
EIRHLR AC
VLRG
F
(G)MSC
E
BSS NSS
Interfaces
ACEIR
BTS
OMC
MSCVLR
HLR
BSC
BTS
BTS
BTS
BTS
BSC
BSS - Base StationSubsystem
NSS - Network Subsystem
NMS - Network Management SystemMS
AbisAir A
IWF
SCPSPDN
PSTNISDN
Transcoder
Generic GSM Architecture
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